Circumferential Displacement Tool System

ABSTRACT

Just above an oil wellbore, an example circumferential displacement tool grips a threaded coupling in performing a circumferential displacement method of properly tightening the coupling to an upper sucker rod and/or to a lower one. In some examples, upper and lower joints of the coupling are tightened sequentially and independently to ensure proper circumferential displacement at each joint. In some examples, during disassembly of a string of rods being withdrawn from the wellbore, the tool can unscrew the coupling selectively from either the upper rod or the lower one. In some examples, a controller monitors the tightening or unscrewing of a joint and derives a joint signature based on a series of torque and rotation readings sampled during the make or break operations. The controller, in some examples, identifies a defective joint by comparing the joint signature to a predetermined reference.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional patent application Ser. No. 61/806,328 filed on Mar. 28, 2013.

FIELD OF THE DISCLOSURE

The subject invention generally pertains to the assembly or disassembly of well strings, such as a string of tubing or sucker rods used in a well, and more specifically pertains to a tool and method for tightening or loosening well string joints.

BACKGROUND

Conventional tongs are used for tightening and loosening joints of a well string, such as a string of tubing or sucker rods used in a wellbore of a well. Tongs usually comprise an assembly of various components and mechanisms such as hydraulic drive units, mechanical gearing and jaws. Some examples of tongs, their various components, and uses are disclosed in U.S. Pat. Nos. 6,374,706; 6,758,095 and 7,519,508; all of which are specifically incorporated herein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram showing an example CDT operating in an example method per the teachings disclosed herein.

FIG. 2 is a perspective diagram showing the CDT of FIG. 1 operating during another stage in the example method.

FIG. 3 is a perspective diagram showing the CDT of FIG. 1 operating during another stage in the example method.

FIG. 4 is a perspective diagram showing the CDT of FIG. 1 operating during another stage in the example method.

FIG. 5 is a perspective diagram showing the CDT of FIG. 1 operating during another stage in the example method.

FIG. 6 is a perspective diagram showing the CDT of FIG. 1 operating during another stage in the example method.

FIG. 7 is a perspective diagram showing the CDT of FIG. 1 operating during another stage in the example method.

FIG. 8 is a perspective diagram showing the CDT of FIG. 1 operating during another stage in the example method.

FIG. 9 is a perspective diagram showing the CDT of FIG. 1 operating during another stage in the example method.

FIG. 10 is a perspective view of one example of circumferential displacement tool in proximity with a sucker rod.

FIG. 11 is a perspective view showing an example coupling clamping mechanism.

FIG. 12 is a perspective view showing example coupling jaws in relation to a coupling.

FIG. 13 is a perspective view showing an example upper jaw mechanism with its rod jaws being connected to each other.

FIG. 14 is a perspective view similar to FIG. 13 but showing the rod jaws engaging the rod flats of an upper sucker rod.

FIG. 15 is a graph showing example joint signatures of assembled joints.

FIG. 16 is a graph showing example joint signatures of disassembled joints.

FIG. 17 is a flow chart illustrating an example CDT method disclosed herein.

FIG. 18 is a flow chart illustrating another example CDT method disclosed herein.

FIG. 19 is a flow chart illustrating another example CDT method disclosed herein.

FIG. 20 is a flow chart illustrating another example CDT method disclosed herein.

FIG. 21 is a flow chart illustrating another example CDT method disclosed herein.

FIG. 22 is a flow chart illustrating another example CDT method disclosed herein.

FIG. 23 is a flow chart illustrating another example CDT method disclosed herein.

FIG. 24 is a flow chart illustrating another example CDT method disclosed herein.

FIG. 25 is a flow chart illustrating another example CDT method disclosed herein.

FIG. 26 is a flow chart illustrating another example CDT method disclosed herein.

DETAILED DESCRIPTION

Although example methods herein are described and illustrated with reference to sucker rods, some example methods also apply to other types of string members, such as tubing.

When assembling a sucker rod 22 to a coupling 24, it is very important that the rod pin be correctly loaded. The rod pin is the thread end of rod 22 which screws into coupling 24. Too much or not enough load may lead to joint failure. Correct loading is achieved when the rod pin is stretched or strained a precise predetermined amount. Stretching the pin places the pin in tension, which causes the shoulder portion of the joint to be under compression. The shoulder portion is the axial interface between rod 22 and coupling 24, and another shoulder portion is between rod 28 and coupling 24. The friction caused by the compression on the shoulder joint surfaces helps prevent the joint from separating when rod 22 is in service.

The proper amount of pin stretch is accomplished by observing the circumferential displacement (CD) of a rod shoulder 48 (FIG. 7) relative to the coupling's outside diameter as rod 22 is tightened beyond the shoulder point (SP). The shoulder point, or SP, refers to the angular relationship between rod 22 and coupling 24 when joint 20 is hand tight. FIG. 7 shows joint 20 hand tight to SP. As joint 20 is further tightened from being just hand tight to fully and properly tightened, the resulting circumferential displacement or CD is the circumferential distance that rod 22 rotates relative to coupling 24. FIG. 9 shows joint 20 fully tightened to a proper CD. One source for recommended CD values is API Spec 11 b, which is a known standard published by the American Petroleum Institute (API). Rod manufactures have also published CD specifications for their products. Sucker rod manufacturers often recommend CD values that are greater than those specified by the API.

In some examples, a circumferential displacement tool 12 (also referred to as CDT 12) engages lower sucker rod 28 (e.g., a first or second rod), upper sucker rod 22 (e.g., a first or second rod), and coupling 24. CDT 12, in some examples, controls the rotational position of both rods 22 and 28 relative to coupling 24. This capability means that some example of CDT 12 can actually set the correct CD on either or both joints 20 and/or 26. CDT 12 includes a lower jaw 18 (e.g., first jaw), an upper jaw 14 (e.g., second jaw), and a middle jaw 16. The terms, “jaw” and “jaws” are used interchangeably because sometimes an example jaw is actually a plurality of jaws such as a pair of opposing jaw elements. Jaws 14, 16 and 18 enable CDT 12 to grasp or engage both upper and lower rod flats 50 and grip the cylindrical surface of coupling 24. In addition to being able to grasp coupling 24 and engage flats 50 of rods 22 and 28; jaws 14, 16 and 18 can be rotated about a vertical axis 52 to make or break either joint 20 or 26, selectively. The term, “make” as it pertains to making a joint refers to assembling or screwing the joint together. The term, “break” as it pertains to breaking a joint refers to disassembling or unscrewing the joint.

Some example versions of CDT 12 include, but are not necessarily limited to: (a) A fully automatic version requiring no manual manipulation of the CDT itself while in use on an automated or robotic rig. (b) A semi-automatic version for use on a conventional rig where an operator would manually engage the CDT with lower rod 28 and initiate the making or breaking process. Once manually engaged, a controller 54 would then automatically control one or more tasks associated with properly making or breaking one or both joints. (c) A manual version where an operator manually controls the operation of CDT 12. Examples of such manual operations include aligning lower jaw 18 with the flats of rod 28; triggering the engagement of jaws 14, 16 and/or 18; and triggering the rotation of jaws 14, 16 and/or 18. Controller 54 (e.g., a computer, a programmable logic controller, an electrical circuit, a switch, a relay, and various combinations thereof) is schematically illustrated to represent any system for providing at least one signal output in response to receiving a signal input. In some examples, controller 54 includes computing means for processing information such as data and sampled readings. In some examples, controller 54 is borne by CDT 12. In some examples, controller 54 is spaced apart from CDT 12.

Some examples of CDT 12 have three operating mechanisms 56, 58 and 60 that are supported by a main frame 62 (FIG. 10). The first is upper rod mechanism 56, which includes upper jaw 14 that engages and holds or rotates upper rod 22. The second is coupling clamping mechanism 56, which includes middle jaw 16 that grasps and holds or rotates coupling 24. The third is lower rod mechanism 60, which includes lower jaw 18 that grasps and holds lower rod 28. By operating these three mechanisms 56, 58 and 60 in the correct sequence, CDT 12 can properly set the CD of either or both joints 20 or 26, selectively. CDT 12 can also break either or both joints 20 or 26, selectively.

Main frame 62 and its cover provide mounting locations and support for one or more additional items. Examples such items include, but are not limited to, handles in manual versions of CDT 12 for aligning lower jaws 18 to the flats of lower rod 28, and control elements such as levers, buttons, and the like.

Upper rod mechanism 56 is common to all three versions of CDT 12. Upper rod mechanism 56 is used to engage flats 50 on upper rod 22 and then rotate rod 22 relative to coupling 24, thereby making or breaking joint 20. When making joint 20, mechanism 56 controllably rotates upper rod 22 relative to coupling 24 to achieve a predetermined proper CD of joint 20. In some examples, upper rod mechanism 56 comprises: (a) one or more jaws 14 that move (e.g., independently or as a unit) to engage or disengage flats 50 on upper rod 22, (b) means for extending or retracting jaw 14 respectively into and out of the engaged position, (c) a base 64 that carries jaw 14 and can rotate about axis 52, and (d) a transmission means 66 for rotating base 64. In some examples, jaw 14 moves to fully engage flats 50 by sliding along a slot 68 (FIG. 5) in base 64. The jaw's movement relative to base 64 and/or the base's movement relative to axis 52 can be driven by various means, examples of which include, but are not limited to, spring force, pneumatic force, hydraulic force, hydraulic or pneumatic cylinder, linear motor, and various combinations thereof.

Transmission means 66 is schematically illustrated to represent any mechanism (e.g., gears, speed reducer, chains, belts, couplings, shafts, levers, clutches, and various combinations thereof) capable of imparting rotational motion to base 64. Some examples of transmission means 66 include an example sector gear 70, as shown in FIGS. 13 and 14. In some examples, transmission means 66 transmits power from a drive unit 72 to base 64. Drive unit 72 is schematically illustrated in FIG. 1 to represent any means for providing power that is ultimately used for rotating base 64. Examples of drive unit 72 include, but are not limited to, a hydraulic motor, a hydraulic pump, a pneumatic motor, a compressor, an electric motor, a gear motor, a hydraulic cylinder, a pneumatic cylinder, and various combinations thereof. In some examples, drive unit 72 comprises a hydraulic pump and a HELAC rotary actuator, wherein the pump supplies hydraulic pressure to the HELAC rotary actuator, which in turn is coupled to transmission means 66. HELAC is a registered trademark of Helac Corporation of Enumclaw, Washington.

To engage flats 50 of upper rod 22, some examples of upper rod mechanism 56 have one or more pneumatic cylinders that bias jaws 14 in the engaged direction, i.e., toward axis 52 of rod 22. Depending on whether jaw(s) 14 moves in unison (e.g., jaw 14 is a unitary piece or connected to act as one) or moves independently (two individual jaws 14) can determine how jaw 14 is rotationally aligned for engagement with flats 50. If jaw 14 moves as a unitary piece, as illustrated, base 64 will rotate until the jaw's flat-engaging surfaces align with the two flats 50 on rod 22, or until base 64 reaches a certain rotational limit (in some examples, base 64 cannot rotate enough in one direction to move jaw 14 into engagement with flats 50). If during a first attempt of rotation, jaws 14 do not engage the rod flats, base 64 will reverse rotation and rotate in the opposite direction until jaws 14 slide into engagement with flats 50. In the automatic and semi-automatic versions of CDT 12, the rotation reversal process is controlled automatically by controller 72. In manual versions of CDT 12, the operator manually determines the direction of rotation.

If jaw 14 is a two-piece set of independent moving jaws, both jaws of the set will be biased in the engaged direction toward axis 52 of rod 22. If both jaws do not fully engage rod flats 50, each jaw will stop at the point they encounter rod flat 50. Sensors of CDT 12 measure the distance traveled by each jaw and inputs that information to controller 54. Based on the measured distances, controller 54 determines the orientation of the rod flats 50 and then rotates base 64 clockwise (CW) or counterclockwise (CCW) to minimize the rotation required to fully engage rod flats 50.

Coupling clamping mechanism 58 is common in various examples of CDT 12, including the automatic version, the semi-automatic, and the manual version. Coupling clamping mechanism 58, in some examples, comprises: (a) a frame 74 (FIG. 12) that supports middle jaw 16 and allows them to be rotated about vertical axis 52; (b) jaws 16 that engage the outside diameter of coupling 24, wherein these clamping jaws, in some examples, grip coupling 24 without appreciably slipping or marring the surface of coupling 24; (c) means for clamping jaws 16 radially against coupling 24; and (d) drive means for imparting rotational motion to frame 74 so that frame 74 and middle jaw 16 can be rotated about axis 52 relative to lower jaw 18. The motive force for such rotation is provided by any suitable means, examples of which include, but are not limited to, one or more hydraulic cylinders, a hydraulic motor, a rotary actuator, a gear motor, etc. Example means for clamping jaws 16 radially against coupling 24 include, but are not limited to, one or more hydraulic cylinders, hydraulic pressure, mechanical clamping mechanisms, spring force, and various combinations thereof.

Once middle jaw 16 is clamped against coupling 24 and upper jaw 14 is engaging flats 50 of upper rod 22, base 64 of upper rod mechanism 56 rotates about axis 52 clockwise or counterclockwise to respectively make or break upper joint 20. The rotation of base 64 is controlled by controller 54 and powered by drive unit 72 through transmission means 66. In some examples, during the process of making or breaking upper joint 20 (or any other chosen joint), the process is monitored by sensors 76 and sensor 78, which respectively sense torque-related information and rotation-related information of CDT 12. The torque-related information or values and the rotation-related information or values are received and processed by controller 54. Controller 54 uses the torque and rotation related information for accurately controlling the tightening process and for analysis. The analysis carried out by controller 54 will be explained later with reference to FIGS. 15 and 16.

Torque-related information (torque-related values 80) are variables that vary as a function of the torque that CDT 12 applies to a joint, such as joint 20 or 26. Examples of torque-related values 80 include, but are not limited to, hydraulic pressure readings and strain gage readings. In some examples, sensor 76 is a pressure sensor sensing the hydraulic pressure of drive unit 72. Example rotation-related information (rotation-related values 82) are variables that vary as a function of the relative rotation or CD at a joint (e.g., joint 20 or 26) between a chosen rod (e.g., rod 22 or rod 28) and coupling 24. In some examples, rotation-related values are any values that vary as a function of how far an element associated with CDT 12 rotates. Examples of such elements include, but are not limited to, upper jaw 14, middle jaw 16, lower jaw 18, upper string member 22, coupling 24, a drive gear of tool 12, etc. Examples of rotation-related values 82 include, but are not limited to, the number of gear teeth passing sensor 78, angular movement or rotation in degrees, encoder readings, resolver readings, etc. Examples of sensor 78 include, but are not limited to, a Hall effect sensor, photoelectric eye, proximity sensor, a counter, etc.

Some example versions of lower rod mechanism 60 include, but are not necessarily limited to: (a) an automatic version, wherein lower rod mechanism 60 is basically the same as upper rod mechanism 56, only inverted and situated near the bottom of CDT 12; (b) a semi-automatic version; and (c) a manual version. The manual and semi-automatic versions are basically the same in that they both have lower rod jaws 18 in a rotationally fixed location relative to frame 62 (FIG. 10); consequently, the operator manually positions CDT 12 (e.g., manually rotates the CDT's frame about axis 52) so that lower rod jaws 18 are in alignment to engage rod flats 50 of lower rod 28. In some examples, lower rod jaws 18 do not slide on a base of a lower rod mechanism 60, and so base 84 is basically omitted or at least does not rotate with respect to frame 62 (FIG. 10) of CDT 12.

In the automatic version of CDT 12, the upper and lower rod mechanisms 56 and 60 are driven by power unit 72 through transmission means 66. In some examples, using one power unit 72 (e.g., one HELAC rotary actuator) to drive both mechanisms 56 and 60 selectively, transmission means 66 includes a commonly shared idler shaft with two idler gears, one per mechanism. This method can be used in examples where only one mechanism 56 or 60 is powered at any one time. In other examples, upper and lower rod mechanisms 56 and 60 are sometimes powered concurrently.

In the semi-automatic and manual versions of CDT 12, the “lower rod mechanism” remains stationary relative to frame 62. Upper rod mechanism 56 in the semi-automatic and manual versions is basically the same as in the automatic version. When only one mechanism of the upper and lower mechanisms is driven, there is no need for the idler gears and shaft; therefore, the output gear of a rotary actuator can drive upper rod mechanism 56 directly by engaging sector gear 70 on base 64.

Altogether, FIGS. 1-14 illustrate a circumferential displacement tool method 10 using circumferential displacement tool 12 that, in some examples, includes upper jaw 14, middle jaw 16 and lower jaw 18 for tightening or loosening upper joint 20 between upper string member 22 and coupling 24 and/or lower joint 26 between coupling 24 and lower string member 28. In some examples, circumferential displacement tool method 10 is illustrated as follows: Arrow 86 of FIG. 1 represents lowering first string member 28 down into a wellbore 88 and a holder 90 gripping, holding or otherwise supporting first string member 28 at a point below coupling 24. Holder 90 is schematically illustrated to represent any device for gripping, holding or otherwise supporting a well string in a wellbore. In some examples, holder 90 includes wedges 92 that can be extended or retracted to selectively grip and release string member 28 for the purpose of raising or lowering a well string 94 or holding well string 94 at a substantially stationary elevation while making or breaking a joint. Some examples of holder 90 are known in the well industry as slips, spiders or elevators (Cavins Oil Well Tools, division of Dawson Enterprises, is of provider of such equipment). FIG. 1 and arrow 30 show lower jaw 18 rotating selectively clockwise or counterclockwise to align itself to lower string member 28. FIG. 2 and arrow 44 show lower jaw 18 engaging lower string member 28. FIG. 3 and arrows 32 show middle jaw 16 gripping coupling 24. FIG. 4 and arrows 34 show middle jaw 16 rotating coupling 24, thereby tightening lower joint 26 to a first predetermined tightened state. FIG. 5 shows after middle jaw 16 rotates coupling 24 and tightens lower joint 26 to the first predetermined tightened state, middle jaw 16 holding coupling 24 substantially stationary. FIG. 6 and arrow 36 show while middle jaw 16 is holding coupling 24 substantially stationary, lower jaw 18 disengaging lower string member 28. FIG. 7 and arrow 38 show while middle jaw 16 is holding coupling 24 substantially stationary, upper jaw 14 rotating selectively clockwise or counterclockwise to align itself to upper string member 22. FIG. 8 and arrow 40 show upper jaw 14 engaging upper string member 22. FIG. 9 and arrow 42 show while middle jaw 16 is still holding coupling 24 substantially stationary, upper jaw 14 rotating upper string member 22, thereby tightening upper joint 20 to a second predetermined tightened state.

FIG. 10 is a perspective view of one example of circumferential displacement tool 12 in proximity with a sucker rod comprising upper string member 22, coupling 24 and lower string member 28. FIG. 11 shows coupling clamping mechanism 58. FIG. 12 shows middle jaws 16 releasing coupling 24. FIG. 13 shows an example CDT 12, wherein upper rod mechanism 56 is driven by sector gear 70, and rod jaws 14 are connected to each other (e.g., the pair of jaws being a unitary piece). FIG. 14 shows upper rod mechanism 56 with its rod jaws 14 engaging the rod flats of an upper sucker rod (upper string member 22).

Returning to FIGS. 15 and 16, some examples of CDT 12 use controller 54 for analyzing data collected by sensors 76 and 78 as CDT 12 makes or breaks a joint (e.g., joint 20 or 26). Line 96 of FIG. 15 is a graphical plot showing how the torque exerted while tightening a normal joint varies with circumferential displacement of the joint. Upon tightening the joint, torque-related values 80 are plotted with reference to the y-coordinate (ordinate), and rotation-related values 82 are plotted with reference to the x-coordinate (abscissa). Associating or pairing the torque-related values 80 with the rotation-related values 82 provides a plurality of torque-rotation data points 98. Point 98 a is at the SP (shoulder point) when the joint was just hand-tight, and point 98 b is at the completion of the tightening process. One or more data points 98 define an actual joint signature 100. In some examples, controller 54 determines the quality of a joint by comparing the actual joint signature 100 to a reference. The reference can be a single value or data point (e.g., a certain pressure value), a plurality of values or data points (e.g., a function, curve, etc.), a range of values, a slope or ratio, an area, a predetermined reference, and/or a reference learned by previously tightening a plurality of earlier joints.

Line 102 of FIG. 15 is a graphical plot similar to line 96 but showing the results of tightening a second joint (e.g., joint 20 or 26), wherein line 96 has one or more characteristic indicating that the second joint is defective. Examples of such characteristics include, but are not limited to, a slope 104 (or inverse thereof) of line 102 near the SP (point 106) deviating significantly from a corresponding slope 108 (or inverse thereof) of line 96, a torque-related value 80 a of line 102 at the final CD deviating significantly from a corresponding torque-related value 80 b of line 96, and/or an area 110 under line 102 deviating significantly from a corresponding area 112 under line 96. In some examples, controller 54 compares the actual characteristics of slope, final torque and/or area to a reference characteristic value. If the comparison is beyond (e.g., greater than, or less than) a predetermined acceptable value, controller 54 provides a visual or audible alert 114 (e.g., a light or horn) indicating that the joint is defective. Example defects include, but are not limited to, a loose joint, an over tightened joint, coupling deformation, rod deformation, worn surfaces, corrosion, galled threads, burr on coupling face, etc.

FIG. 16 is similar to FIG. 15; however, lines 116 and 118 reflect torque-related values 80 and rotation-related values 82 of a joint (e.g., joint 20 or 26) being unscrewed. Line 116 indicates its respective joint is normal and acceptable. Line 118, however, has one or more characteristic indicating that its respective joint is defective. Examples of such characteristics include, but are not limited to, an area 120 under line 118 deviating significantly from a corresponding area 122 under line 116, an almost flat segment 124 of line 118 near the SP (point 126) being longer than a corresponding flat segment 128 of line 116, a peak torque-related value 130 of line 118 deviating significantly from a corresponding peak torque-related value 132 of line 116, and/or a broader peak region 134 of line 118 deviating significantly from a corresponding peak region 136 of line 116.

In some examples, controller 54 compares the actual characteristics of area under the curve, flat segment near SP, and/or peak torque to a reference characteristic value. If the comparison is beyond (e.g., greater than, or less than) a predetermined acceptable value, controller 54 provides a visual or audible alert 114 (e.g., a light or horn) indicating that the unscrewed joint is defective. Again, example defects include, but are not limited to, a loose joint, an over tightened joint, coupling deformation, rod deformation, worn surfaces, corrosion, galled threads, burr on coupling face, etc. Being able to automatically identify a defective joint during disassembly avoids having to contend with the discovery later during re-assembly of the well string.

Referring to FIG. 17, some examples of method 10 involve gripping coupling 24 so that a threaded joint (e.g., joint 20 or 26) can be precisely tightened to a specified CD. More specifically, block 138 of method 10 represents extending first string member 28 and/or second string member 22 down into wellbore 88. Block 140 represents holder 90 gripping, holding or otherwise supporting string member 28 or 22 at a point below coupling 24. Block 142 represents, while string member 28 or 22 is extending down into wellbore 88, middle jaw 16 gripping coupling 24. Block 144 represents, while middle jaw 16 is gripping coupling 24, second jaw 14 engaging second string member 22. Block 146 represents forcing relative rotation between second jaw 14 and middle jaw 16, thereby forcing relative rotation between second string member 22 and coupling 24.

Referring to FIG. 18, some examples of method 10 involve CDT 12 using three sets of jaws (upper jaw 14, middle jaw 16 and lower jaw 18) to tighten joints above and below coupling 24, and doing so sequentially. Specifically, block 148 of method 10 represents extending first string member 28 down into wellbore 88 while second string member 22 is above wellbore 88. Block 150 represents holder 90 gripping, holding or otherwise supporting first string member 28 at a point below coupling 24. Block 152 represents, while first string member 28 is extending down into wellbore 88, middle jaw 16 gripping coupling 24. Block 154 represents first jaw 18 engaging first string member 28 while middle jaw 16 is gripping coupling 24. Block 156 represents middle jaw 16 tightening first joint 26 by rotating coupling 24 relative to first string member 28. Block 158 represents second jaw 14 engaging second string member 22 while middle jaw 16 is gripping coupling 24. Block 160 represents second jaw 14 tightening second joint 20 by rotating second string member 22 relative to coupling 24, wherein middle jaw 16 tightening first joint 26 and second jaw 14 tightening second joint 20 are performed sequentially while first string member 28 is extending down into wellbore 88 and second string member 22 is above wellbore 88.

Referring to FIG. 19, some examples of method 10 use the CDT's ability to rotate both its upper rod jaws 14 and its coupling jaws 16. Specifically, block 162 represents lowering first string member 28 down into wellbore 88. Block 164 represents coupling 24 extending above first string member 28. Block 166 represents second string member 22 extending above coupling 24. Block 168 represents first jaw 18 selectively engaging and disengaging first string member 28. Block 170 represents second jaw 14 selectively engaging and disengaging second string member 22. Block 172 represents middle jaw 16 selectively gripping and releasing coupling 24. Block 174 represents rotating middle jaw 16 relative to frame 62, first jaw 18, and second jaw 14. Block 176 represents rotating second jaw 14 relative to frame 62, middle jaw 16, and first jaw 18. Block 178 represents rotating first jaw 18 relative to frame 62, middle jaw 16, and second jaw 14. Block 180 represents second jaw 14 rotating first string member 22 relative to frame 62. Block 182 represents middle jaw 16 holding coupling 24 at a substantially fixed rotational position relative to frame 62 while second jaw 14 rotates first string member 22. Block 184 represents middle jaw 16 rotating coupling 24 relative to frame 62. Block 186 represents first jaw 18 holding first string member 28 at a substantially fixed rotational position relative to frame 62 while middle jaw 16 rotates coupling 24.

Referring to FIG. 20, some examples of method 10 use the CDT's ability to operate selectively in a lower break mode and an upper break mode, whereby CDT 12 can selectively unscrew either joint above or below coupling 24. Specifically, block 188 represents first jaw 18 selectively engaging and disengaging first string member 28. Block 190 represents second jaw 14 selectively engaging and disengaging second string member 22. Block 192 represents middle jaw 16 selectively gripping and releasing coupling 24. Block 194 represents, in the lower break mode, middle jaw 16 unscrewing coupling 24 from first string member 28 at first joint 26 by rotating coupling 24 relative to first string member 28. Block 196 represents, in the upper break mode, second jaw 14 unscrewing second string member 22 from coupling 24 at second joint 20 by rotating second string member 22 relative to coupling 24.

Referring to FIG. 21, some examples of method 10 use controller 54 for determining an acceptable or defective joint by collecting torque-related and rotation-related data as the joint is being tightened. From that data, controller 54 derives a joint signature of the tightened joint. Controller 54 compares the joint signature to a reference signature or some other reference in determining the quality or condition of the joint. Specifically, block 198 represents extending first string member 28 down into wellbore 88 while second string member 22 is above the wellbore. Block 200 represents the holder 90 gripping, holding or otherwise supporting first string member 28 at a point below coupling 24. Block 202 represents while first string member 28 is extending down into wellbore 88, the middle jaw 16 gripping coupling 24. Block 204 represents second jaw 14 engaging second string member 22 while middle jaw 16 is gripping coupling 24. Block 206 represents second jaw 14 tightening second joint 20 by rotating second string member 22 relative to coupling 24. Block 208 represents controller 54 recording a plurality of torque-related values 80 pertaining to second jaw 14 tightening second joint 20. Block 210 represents controller 54 recording a plurality of rotation-related values 82 pertaining to second string member 22 rotating relative to coupling 24. Block 212 represents controller 54 associating the plurality of torque-related values 80 with the plurality of rotation-related values 82 to create a plurality of torque-rotation data points 98 that provide an actual joint signature 100 of second joint 20 being tightened. Block 214 represents controller 54 computing a comparison by comparing the actual joint signature 100 to a reference. Block 216 represents controller 54 providing alert signal 114 if the comparison is beyond a predetermined acceptable value.

Referring to FIG. 22, some examples of method 10 use the CDT's ability to rotate its lower jaws 18 selectively clockwise or counterclockwise as an effective way of aligning lower jaws 18 to the flats of lower sucker rod 28. Specifically, block 218 represents lowering first string member 28 down into wellbore 88. Block 220 represents coupling 24 extending above first string member 28. Block 222 represents second string member 22 extending above coupling 24. Block 224 represents, relative to frame 62, first jaw 18 rotating about a substantially vertical axis 52 selectively clockwise and counterclockwise to align itself to the flats of first string member 28.

Referring to FIG. 23, some examples of method 10 identify a defective joint by monitoring a torque-related variable as the joint is being unscrewed. Specifically, block 226 represents extending first string member 28 or second string member 22 down into wellbore 88. Block 228 represents circumferential displacement tool 12 unscrewing second joint 20. Block 230 represents, while unscrewing second joint 20, controller 54 recording a torque-related value 80 pertaining to the unscrewing of second joint 20. Block 232 represents controller 54 computing a comparison by comparing the torque-related value 80 to a reference. Block 234 represents controller 54 providing alert signal 114 if the comparison is beyond a predetermined acceptable value.

Referring to FIG. 24, some examples of method 10 identify a defective joint by monitoring a torque-related variable 80 and a rotation-related variable 82 as the joint is being unscrewed. Controller 54, in some examples, derives a joint signature based on a plurality of torque-related values and rotation-related values. Controller 54 compares the joint signature to a reference signature or some other reference in determining the quality or condition of the unscrewed joint. Specifically, block 236 represents extending first string member 28 or second string member 22 down into wellbore 88. Block 238 represents CDT 12 unscrewing second joint 20. Block 240 represents, while unscrewing second joint 20, controller 54 recording a plurality of torque-related values pertaining to the unscrewing of second joint 20. Block 242 represents, while unscrewing second joint 20, controller 54 recording a plurality of rotation-related values pertaining to the unscrewing of second joint 20. Block 244 represents controller 54 associating the plurality of torque-related values with the plurality of rotation-related values to create a plurality of torque-rotation data points 286 that provide an actual joint signature 288 of second joint 20 being unscrewed. Block 246 represents controller 54 computing a comparison by comparing actual joint signature 288 to a reference. Block 248 represents controller 54 providing alert signal 114 if the comparison is beyond a predetermined acceptable value.

Referring to FIG. 25, some examples of method 10 use CDT 12 in tightening two joints 20 and 26 simultaneously but terminating the tightening of one joint before the other. Specifically, block 250 represents extending first string member 28 down into wellbore 88 while second string member 22 is above wellbore 88. Block 252 represents holder 90 gripping, holding or otherwise supporting first string member 28 at a point below coupling 24. Block 254 represents, while first string member 28 is extending down into wellbore 88, middle jaw 16 gripping coupling 24. Block 256 represents first jaw 18 engaging first string member 28 while middle jaw 16 is gripping coupling 24. Block 258 represents middle jaw 16 tightening first joint 26 by rotating coupling 24 relative to first string member 28. Block 260 represents second jaw 14 engaging second string member 22 while middle jaw 16 is gripping coupling 24. Block 262 represents second jaw 14 tightening second joint 20 by rotating second string member 22 relative to coupling 24, wherein middle jaw 16 tightening first joint 26 and second jaw 14 tightening second joint 20 are performed concurrently. Block 264 represents controller 54 terminating the middle jaw 16 tightening first joint 26. Block 266 represents controller 54 terminating the second jaw 14 tightening second joint 20, wherein terminating the tightening of first joint 26 and terminating the tightening of second joint 20 occur at different times.

Referring to FIG. 26, some examples of method 10 include blocks 268-284, wherein block 268 represents lower jaw 18 rotating to align itself to lower string member 28. Block 270 represents lower jaw 18 engaging lower string member 28. Block 272 represents middle jaw 16 gripping coupling 24. Block 274 represents middle jaw 16 rotating coupling 24, thereby tightening lower joint 26. Block 276 represents, after middle jaw 16 rotates coupling 24 and tightens lower joint 26 to a first predetermined tightened state, middle jaw 16 holding coupling 24 substantially stationary relative to frame 62. Block 278 represents, while middle jaw 16 is holding coupling 24 substantially stationary relative to frame 62, lower jaw 18 disengaging lower string member 28. Block 280 represents, while middle jaw 16 is holding coupling 24 substantially stationary relative to frame 62, upper jaw 14 rotating to align itself to upper string member 22. Block 282 represents upper jaw 14 engaging upper string member 22. Block 284 represents, while middle jaw 16 is still holding coupling 24 substantially stationary relative to frame 62, upper jaw 14 rotating upper string member 22, thereby tightening upper joint 20.

Although the invention is described with respect to a preferred example embodiment, modifications thereto will be apparent to those of ordinary skill in the art. It should be noted, for instance, that the method blocks shown in FIGS. 17-26 are not necessarily in any particular order and do not necessarily have to be performed in any particular sequence. The scope of the invention, therefore, is to be determined by reference to the following claims: 

1. A circumferential displacement tool method using at least one of a circumferential displacement tool, a holder, and a controller at a wellbore, the circumferential displacement tool includes at least one of a first jaw, a middle jaw and a second jaw for tightening or loosening at least one of a first joint and a second joint, wherein the first joint is between a first string member and a coupling, the second joint is between the coupling and a second string member, and the coupling couples the first string member to the second string member, the circumferential displacement tool method comprising: extending at least one of the first string member and the second string member down into the wellbore; the holder supporting one of the first string member and the second string member at a point below the coupling; while at least one of the first string member and the second string member is extending down into the wellbore, the middle jaw gripping the coupling; while the middle jaw is gripping the coupling, the second jaw engaging the second string member; and forcing relative rotation between the second jaw and the middle jaw, thereby forcing relative rotation between the second string member and the coupling.
 2. The circumferential displacement tool method of claim 1, wherein forcing relative rotation between the second jaw and the middle jaw involves rotating the second jaw while the first string member is extending down into the wellbore with the second string member being above the first string member.
 3. The circumferential displacement tool method of claim 1, wherein forcing relative rotation between the second jaw and the middle jaw involves rotating the middle jaw while the second string member is extending down into the wellbore with the first string member being above the second string member.
 4. A circumferential displacement tool method using at least one of a circumferential displacement tool, a holder, and a controller at a wellbore, the circumferential displacement tool includes at least one of a first jaw, a middle jaw and a second jaw for tightening or loosening at least one of a first joint and a second joint, wherein the first joint is between a first string member and a coupling, the second joint is between the coupling and a second string member, and the coupling couples the first string member to the second string member, the circumferential displacement tool method comprising: extending the first string member down into the wellbore while the second string member is above the wellbore; the holder supporting the first string member at a point below the coupling; while the first string member is extending down into the wellbore, the middle jaw gripping the coupling; the first jaw engaging the first string member while the middle jaw is gripping the coupling; the middle jaw tightening the first joint by rotating the coupling relative to the first string member; the second jaw engaging the second string member while the middle jaw is gripping the coupling; and the second jaw tightening the second joint by rotating the second string member relative to the coupling, wherein the middle jaw tightening the first joint and the second jaw tightening the second joint are performed sequentially while the first string member is extending down into the wellbore and the second string member is above the wellbore.
 5. A circumferential displacement tool method using at least one of a circumferential displacement tool, a holder, and a controller at a wellbore, the circumferential displacement tool includes at least one of a frame, a first jaw, a middle jaw and a second jaw for tightening or loosening at least one of a first joint and a second joint, wherein the first joint is between a first string member and a coupling, the second joint is between the coupling and a second string member, and the coupling couples the first string member to the second string member, the circumferential displacement tool method comprising: lowering the first string member down into the wellbore; the coupling extending above the first string member; the second string member extending above the coupling; the first jaw selectively engaging and disengaging the first string member; the second jaw selectively engaging and disengaging the second string member; the middle jaw selectively gripping and releasing the coupling; rotating the middle jaw relative to the frame, the first jaw, and the second jaw; and rotating the second jaw relative to the frame, the middle jaw, and the first jaw.
 6. The circumferential displacement tool method of claim 5, further comprising rotating the first jaw relative to the frame, the middle jaw, and the second jaw.
 7. The circumferential displacement tool method of claim 5, further comprising: the second jaw rotating the second string member relative to the frame; and the middle jaw holding the coupling at a substantially fixed rotational position relative to the frame while the second jaw rotates the second string member.
 8. The circumferential displacement tool method of claim 5, further comprising: the middle jaw rotating the coupling relative to the frame; and the first jaw holding the first string member at a substantially fixed rotational position relative to the frame while the middle jaw rotates the coupling.
 9. A circumferential displacement tool method using at least one of a circumferential displacement tool, a holder, and a controller at a wellbore; the circumferential displacement tool having selectively an upper break mode and a lower break mode; the circumferential displacement tool includes at least one of a first jaw, a middle jaw and a second jaw for tightening or loosening at least one of a first joint and a second joint; wherein the first joint is between a first string member and a coupling, the second joint is between the coupling and a second string member, and the coupling couples the first string member to the second string member; the circumferential displacement tool method comprising: the first jaw selectively engaging and disengaging the first string member; the second jaw selectively engaging and disengaging the second string member; the middle jaw selectively gripping and releasing the coupling; in the lower break mode, the middle jaw unscrewing the coupling from the first string member at the first joint by rotating the coupling relative to the first string member; and in the upper break mode, the second jaw unscrewing the second string member from the coupling at the second joint by rotating the second string member relative to the coupling.
 10. A circumferential displacement tool method using at least one of a circumferential displacement tool, a holder, and a controller at a wellbore, the circumferential displacement tool includes at least one of a frame, a first jaw, a middle jaw and a second jaw for tightening or loosening at least one of a first joint and a second joint, wherein the first joint is between a first string member and a coupling, the second joint is between the coupling and a second string member, and the coupling couples the first string member to the second string member, the circumferential displacement tool method comprising: extending the first string member down into the wellbore while the second string member is above the wellbore; the holder supporting the first string member at a point below the coupling; while the first string member is extending down into the wellbore, the middle jaw gripping the coupling; the second jaw engaging the second string member while the middle jaw is gripping the coupling; the second jaw tightening the second joint by rotating the second string member relative to the coupling; the controller recording a plurality of torque-related values pertaining to the second jaw tightening the second joint; the controller recording a plurality of rotation-related values pertaining to the second string member rotating relative to the coupling; the controller associating the plurality of torque-related values with the plurality of rotation-related values to create a plurality of torque-rotation data points that provide an actual joint signature of the second joint being tightened; the controller computing a comparison by comparing the actual joint signature to a reference; and the controller providing an alert signal if the comparison is beyond a predetermined acceptable value.
 11. The circumferential displacement tool method of claim 10, wherein the reference is a slope value based on a delta-torque divided by a delta-rotation, wherein the delta-torque is a change in two torque-related values of the plurality of torque-related values, and the delta-rotation is a change in two rotation-related values of the plurality of rotation-related values.
 12. The circumferential displacement tool method of claim 11, wherein at least one of the two torque-related values and at least one the two rotation-related values were recorded prior to completion of the second joint being tightened.
 13. The circumferential displacement tool method of claim 10, wherein the reference is a pressure value.
 14. The circumferential displacement tool method of claim 10, wherein the plurality of torque-related values are a plurality of pressure readings sampled by the controller.
 15. The circumferential displacement tool method of claim 10, wherein the reference is a predetermined change in rotation-related values for a predetermined change in pressure.
 16. The circumferential displacement tool method of claim 10, wherein the actual joint signature is a graphical plot, and the controller computing the comparison involves comparing an area under the graphical plot to the reference.
 17. A circumferential displacement tool method using at least one of a circumferential displacement tool, a holder, and a controller at a wellbore, the circumferential displacement tool includes at least one of a frame, a first jaw, a middle jaw and a second jaw for tightening or loosening at least one of a first joint and a second joint, wherein the first joint is between a first string member and a coupling, the second joint is between the coupling and a second string member, and the coupling couples the first string member to the second string member, the circumferential displacement tool method comprising: lowering the first string member down into the wellbore; the coupling extending above the first string member; the second string member extending above the coupling; and relative to the frame, the first jaw rotating about a substantially vertical axis selectively clockwise and counterclockwise to align itself to the first string member.
 18. The circumferential displacement tool method of claim 17, wherein the first string includes a set of flats to which the first jaw aligns itself.
 19. A circumferential displacement tool method using at least one of a circumferential displacement tool, a holder, and a controller at a wellbore, the circumferential displacement tool includes at least one of a frame, a first jaw, a middle jaw and a second jaw for tightening or loosening at least one of a first joint and a second joint, wherein the first joint is between a first string member and a coupling, the second joint is between the coupling and a second string member, and the coupling couples the first string member to the second string member, the circumferential displacement tool method comprising: extending one of the first string member and the second string member down into the wellbore; the circumferential displacement tool unscrewing the second joint; while unscrewing the second joint, the controller recording a torque-related value pertaining to the unscrewing of the second joint; the controller computing a comparison by comparing the torque-related value to a reference; and the controller providing an alert signal if the comparison is beyond a predetermined acceptable value.
 20. A circumferential displacement tool method using at least one of a circumferential displacement tool, a holder, and a controller at a wellbore, the circumferential displacement tool includes at least one of a frame, a first jaw, a middle jaw and a second jaw for tightening or loosening at least one of a first joint and a second joint, wherein the first joint is between a first string member and a coupling, the second joint is between the coupling and a second string member, and the coupling couples the first string member to the second string member, the circumferential displacement tool method comprising: extending one of the first string member and the second string member down into the wellbore; the circumferential displacement tool unscrewing the second joint; while unscrewing the second joint, the controller recording a plurality of torque-related values pertaining to the unscrewing of the second joint; while unscrewing the second joint, the controller recording a plurality of rotation-related values pertaining to the unscrewing of the second joint; the controller associating the plurality of torque-related values with the plurality of rotation-related values to create a plurality of torque-rotation data points that provide an actual joint signature of the second joint being unscrewed; the controller computing a comparison by comparing the actual joint signature to a reference; and the controller providing an alert signal if the comparison is beyond a predetermined acceptable value.
 21. A circumferential displacement tool method using at least one of a circumferential displacement tool, a holder, and a controller at a wellbore, the circumferential displacement tool includes at least one of a first jaw, a middle jaw and a second jaw for tightening or loosening at least one of a first joint and a second joint, wherein the first joint is between a first string member and a coupling, the second joint is between the coupling and a second string member, and the coupling couples the first string member to the second string member, the circumferential displacement tool method comprising: extending the first string member down into the wellbore while the second string member is above the wellbore; the holder supporting the first string member at a point below the coupling; while the first string member is extending down into the wellbore, the middle jaw gripping the coupling; the first jaw engaging the first string member while the middle jaw is gripping the coupling; the middle jaw tightening the first joint by rotating the coupling relative to the first string member; the second jaw engaging the second string member while the middle jaw is gripping the coupling; the second jaw tightening the second joint by rotating the second string member relative to the coupling, wherein the middle jaw tightening the first joint and the second jaw tightening the second joint are performed concurrently; the controller terminating the middle jaw tightening the first joint; and the controller terminating the second jaw tightening the second joint, wherein terminating the tightening of the first joint and terminating the tightening of the second joint occur at different times.
 22. A circumferential displacement tool method using a circumferential displacement tool that includes a frame, an upper jaw, a middle jaw and a lower jaw for tightening or loosening an upper joint between an upper string member and a coupling and a lower joint between the coupling and a lower string member, the circumferential displacement tool method comprising: the lower jaw rotating to align itself to the lower string member; the lower jaw engaging the lower string member; the middle jaw gripping the coupling; the middle jaw rotating the coupling, thereby tightening the lower joint; after the middle jaw rotates the coupling and tightens lower joint to the first predetermined tightened state, the middle jaw holding the coupling substantially stationary relative to the frame; while the middle jaw is holding the coupling substantially stationary relative to the frame, the upper jaw rotating to align itself to the upper string member; the upper jaw engaging the upper string member; and while the middle jaw is still holding the coupling substantially stationary relative to the frame, the upper jaw rotating the upper string member, thereby tightening the upper joint.
 23. The circumferential displacement tool method of claim 22, wherein the lower string member is a sucker rod.
 24. The circumferential displacement tool method of claim 22, wherein the lower string member is a tube. 